This invention relates to a clamp type galvanometer for measuring the electric current in a wire by inserting the wire into an opening in a split iron core set in the device.
Generally, in the clamp type galvanometers using a current transformer with a split iron core, the magnetic resistance at the core joint becomes higher than that at the other parts to increase the residual current, and make the device susceptible to the influence of the external magnetic fields created by the neighboring wires, so that it was hardly possible with said type of conventional galvanometers to correctly measure a zero-phase current or a slight leak current flowing in a grounding conductor.